TONE COMPOSITION.

95

physical apparatus advertise just such instru-ments.

Helmholtz also contrived a set of tuning-forks,which, when bowed, will give out the vowelsounds like the voice.

It was remarked upon p. 89 that it has gen-erally been considered that age has a mellow-ing effect upon the sound of a violin. Once inpossession of the facts concerning sound thathave been alluded to on the preceding pages,it is easy to see how such an opinion should arise,and also the fallacy of it. It is proved conclu-sively that the ability to hear high sounds de-creases as one grows older. As the violin givesa very great number of overtones, even up to thelimits of audibility, it is plain that if such aninstrument should not change in its quality oftone in the least degree, yet to a man who playedupon it for a number of years it would seem tochange by subtracting some of the higher over-tones from the sound; that is, it would seem tobecome mellower. There is no evidence thatsuch a physical change takes place in the instru-ment. It is not here affirmed that no change